The present invention relates generally to systems for hiding data in media and more specifically to a system for multi-layer data hiding in multimedia signals.
With the increasing spread in electronic commerce, there has been a commensurate increase in electronic copying technology. Digital copy technology such as DVD-R, DVD-RW, CD-R, and CD-RW is now widely available. Ensuring the protection of electronic media from unauthorized copying and modification continues to become more important as electronic commerce continues to spread into every area of the national economy. Electronic networks such as the Internet have now become a commonplace medium for conducting the nations"" business, including activities such as the sale of various forms of multimedia products. Examples of multimedia products that can be purchased over the Internet include video and audio compositions as well as images. Also, the mere distribution of multimedia products in a digital format such as CD-ROM and DVD disks exposes the product to potential copying. In an attempt to ensure the secure distribution of multimedia products, content protection mechanisms are increasingly being employed.
Data hiding is one form of content protection that is sometimes employed for copy control and copyright protection. The single pass embedding of passive data such as a watermark into a host medium is one example of data hiding. An embedded watermark is typically intended to provide copyright control and access control of the multimedia product. Unfortunately, present forms of data hiding suffer from numerous drawbacks that reduce the effectiveness of the intended protection and sometimes make the protection technique untenable in real-life applications.
Conventional single pass techniques of embedding one layer of hidden data into a host signal for controlling the use of the host signal generally result in inconsistent protection. In some situations, after unauthorized copying of the host data a false positive signal is received indicating that the pirated copy is an authorized product. Moreover, single pass/single layer techniques can only fulfill (and most likely just partially fulfill) a single purpose, such as ownership protection, access control, and annotation. In addition, controllability of the embedded hidden data is generally not feasible. With regards to capacity, previous single pass/single layer techniques usually are only good for the ideal case such as when images are of same size and when the same amount of data is embedded into each frame of video data.
The present data hiding system and method provides a method for embedding multiple layers of hidden data into multimedia data. First, a media unit of the multimedia data is evaluated to determine an appropriate embedding procedure. Next during a first embedding pass, a ruling layer of primary hidden data is embedded into the media unit. In another embedding pass, a governing layer of secondary hidden data is embedded on top of the ruling layer. The secondary hidden data provides control information for controlling the primary hidden data and the host data.